Crude oil contains various components such as low boiling point light oil and high boiling point heavy oil. In recent years, crude oil with a high content of heavy oil (petroleum heavy oil) is increasingly supplied as crude oil. On the other hand, with regard to oil demand, the demand for light oil is still high. Therefore, a method for producing light oil from petroleum heavy oil is attracting attention.
For a method of producing light oil from petroleum heavy oil, a method of hydrocracking a raw material slurry acquired by adding an iron-based catalyst to petroleum heavy oil has been proposed (see Japanese Laid-Open Patent Publication No. 2001-89772). This conventional method for hydrocracking can efficiently remove heavy metals such as nickel and vanadium contained in the petroleum heavy oil. Additionally, this conventional method for hydrocracking is excellent in economy because a supply of a new catalyst can be suppressed by reusing the used iron-based catalyst.
However, since the catalytic activity of the reused iron-based catalyst is lower than that of the new catalyst, a supply amount of the new catalyst cannot sufficiently be reduced.